Robot-assisted curved surface laser metal deposition process thermal-mechanical coupling simulation method

Abstract

The invention provides a thermal-mechanical coupling simulation method for a robot-assisted curved surface laser metal deposition process, and belongs to the technical field of laser metal deposition. Calibrating the sectional dimension of the deposition channel; discretizing a continuous simulated deposition path into a plurality of sections, scanning on the curved surface substrate along the discrete path by using the calibrated deposition channel section to form a deposition layer body, and obtaining a geometric model containing the curved surface substrate and a deposition layer; meshing and optimizing the geometric model; setting material attributes, boundary conditions and laser paths of the substrate and the deposition layer, and pre-writing the material attributes in the deposition layer body and hiding the material attributes; and performing laser metal deposition simulation, synchronously activating the material attributes of the substrate and the deposition layer in the laser action area along with the movement of the laser action origin, and calculating to obtain an evolution result of the stress field and the temperature field. According to the method, the calculation precision and efficiency are comprehensively planned, the curved surface free path deposition process modeling is realized, and the evolution conditions of a stress field and a temperature field can be accurately predicted.

Description

Technical Field

[0001] The present invention relates to the technical field of laser metal deposition, and in particular to a thermal-mechanical coupling simulation method for a robot-assisted curved surface laser metal deposition process. Background Art

[0002] Laser metal deposition, with its high deposition rate and multi-scenario application potential, has achieved significant development in areas such as industrial repair and the fabrication of complex-shaped components. Laser metal deposition involves complex physical changes and is a multi-scale, multi-physics coupled process. A comprehensive study of this process is challenging, requiring consideration of factors such as the interaction between the material and the energy source, the flow dynamics of the melt pool, and heat conduction between components. Currently, research on the laser metal deposition process is primarily conducted experimentally, which involves numerous steps, is time-consuming, and faces numerous uncertainties and error factors.

[0003] Numerical modeling of thermomechanical coupling for laser metal deposition processes offers a cost-effective, concise, and effective approach for analyzing process physical characteristics and optimizing process parameters and machining strategies. Existing numerical modeling approaches generally involve coupling three components: heat source-material interaction, melt pool morphology dynamics, and microstructural modeling. Due to computational cost constraints, these models often require simplified assumptions about the material, melt pool, and heat conduction, and typically focus on modeling at a single scale based on practical needs.

[0004] With the development of robot-assisted additive manufacturing systems, the application frequency of laser metal deposition processes in the design and manufacture of complex components, especially curved components, has gradually increased. In order to save computing costs, existing technical solutions tend to build models based on simple geometric shapes. There is still a lack of methods for problems such as laser path planning, material deposition process and physical field evolution of complex-shaped curved components in the laser metal deposition process. Based on existing computing resources, the workload and computing cost of building a complete model are very high. In most cases, the model needs to balance between computing speed and accuracy. Therefore, existing modeling solutions basically need to adjust the focus of the model according to its research purpose. In addition, due to the complexity of the laser metal deposition process, a series of highly simplified assumptions need to be used in numerical modeling and simulation, which greatly limits the physical reduction and characterization accuracy of the model. Summary of the Invention

[0005] In order to solve the above problems, the present invention proposes a robot-assisted curved surface laser metal deposition process thermal-mechanical coupling simulation method. The present invention coordinates calculation accuracy and efficiency, realizes the modeling of the curved surface free path deposition process, and can accurately predict the evolution of stress field and temperature field.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention proposes a thermal-mechanical coupling simulation method for a robot-assisted curved surface laser metal deposition process, comprising the following steps:

[0008] Step 1: calibrate the cross-sectional dimensions of the deposition track. During the calibration process, two partially overlapping deposition tracks are used as references to obtain a rectangular calibration dimension, and half of the height and width of the rectangular calibration dimension are taken as the cross-sectional dimensions of the deposition track.

[0009] Step 2: A continuous simulated deposition path is obtained based on the robot data, and the continuous path is discretized into several segments. The calibrated deposition path cross section is used to scan along the discrete path on the curved substrate to form the deposition layer shape, thereby obtaining a geometric model including the curved substrate and the deposition layer.

[0010] Step 3: Initially mesh the geometric model and optimize the mesh using corner refinement and adaptive methods;

[0011] Step 4: Set the material properties, boundary conditions, and laser path of the substrate and deposition layer, pre-write the material properties of the substrate and deposition layer into the deposition layer shape, and hide them;

[0012] Step 5: Perform laser metal deposition simulation based on the laser path and boundary conditions. As the laser action origin moves, the material properties of the substrate and deposited layer in the laser action area are synchronously activated, and the evolution results of the stress field and temperature field of the curved surface laser metal deposition process as the laser action area moves are calculated.

[0013] As a preferred embodiment of the present invention, the calibration process uses two partially overlapping deposition tracks as a reference to obtain the rectangular calibration size, including:

[0014] The actual two partially overlapping sedimentary trace samples were obtained in a pre-experimental manner;

[0015] Use a microscope to calibrate the cross-sectional outer contour and area of ​​the deposition channel sample;

[0016] The height of the rectangular calibration size is determined by taking 90%-97% of the highest point height of the cross-section outer contour as the height, and the width of the rectangular calibration size is determined by the approximate area to obtain the rectangular calibration size;

[0017] The difference between the area of ​​the rectangle at the rectangular calibration size and the cross-sectional area of ​​the deposition track sample is within a preset threshold range.

[0018] As a preferred embodiment of the present invention, the method of obtaining a continuous simulated deposition path according to robot data includes:

[0019] Acquiring robot data, wherein the robot data includes discrete coordinate points of the robot's mechanical arm action position;

[0020] The discrete coordinate points are interpolated into a curve to generate a continuous simulated deposition path.

[0021] As a preferred embodiment of the present invention, after forming a deposition layer shape by scanning along a discrete path on a curved substrate using a calibrated deposition path cross section, the method further includes:

[0022] The overlapping interference between sedimentary layer shapes is eliminated through Boolean operation.

[0023] As a preferred embodiment of the present invention, the method of optimizing the grid by using the angle refinement and adaptive method includes:

[0024] For the initially divided mesh, refine the mesh with sharp corners and large curvature;

[0025] The grid density is adaptively adjusted according to the accuracy requirements of the geometric model. The higher the accuracy requirement, the greater the grid density.

[0026] As a preferred embodiment of the present invention, the boundary conditions include a heat transfer part and a stress part, the heat transfer part includes a heat radiation boundary, a heat convection boundary and a phase change latent heat boundary, and the stress part includes an elastic stress boundary and a stress boundary generated by inelastic thermal strain and plastic strain.

[0027] As a preferred embodiment of the present invention, the laser path is obtained by matching the discrete coordinate points of the simulated deposition path with the time variable based on the laser speed.

[0028] As a preferred embodiment of the present invention, during the laser metal deposition simulation process, the range of the laser action area is not less than the range of the deposition path cross-sectional size. As the laser action origin moves, it is determined whether the grid center point is within the laser action area. If so, the material properties of the grid unit are activated, otherwise they continue to be hidden.

[0029] As a preferred embodiment of the present invention, the laser action surface is set as the lower surface of the deposition path, and the direction of the laser beam is always perpendicular to the action surface.

[0030] In a second aspect, the present invention proposes a robot-assisted curved surface laser metal deposition process thermal-mechanical coupling simulation system for implementing the above-mentioned thermal-mechanical coupling simulation method.

[0031] The beneficial effects of the present invention are:

[0032] The present invention is aimed at complex curved surface components. It calibrates the cross-sectional dimensions of the deposition paths by using two partially overlapping deposition paths as references, and freely models the curved deposition paths by scanning the calibrated rectangular cross-sections along the simulated deposition paths, thereby improving the modeling freedom and effectively adapting to the flexibility of robot-assisted manufacturing.

[0033] The present invention simulates the deposition path through discretization, regards each discretized segment as an analysis step to be solved, and decomposes the deposition process with single-pass deposition as the discrete unit. First, the material properties of the substrate and the deposition layer are hidden. Then, during the laser metal deposition simulation process, the material properties of the substrate and the deposition layer in the laser action area are synchronously activated as the laser action origin moves. Based on a macroscopic perspective, the robot-assisted laser metal deposition process of curved surface components is numerically modeled to achieve accurate prediction of the temperature field and stress field in the deposition area. This method can be applied to manufacturing processes under different process conditions and has high universality.

[0034] The present invention is of great significance to the research on robot-assisted laser metal deposition process, and provides a reference value for analyzing the physical characteristics of the laser metal deposition process, seeking optimal process parameters and optimizing processing strategies. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a flowchart of a thermal-mechanical coupling simulation method for a robot-assisted curved surface laser metal deposition process in an embodiment of the present invention.

[0036] Figure 2 Schematic diagram of the cross-sectional dimension calibration of the deposition channel in an embodiment of the present invention.

[0037] Figure 3 Schematic diagram of multi-pass parallel deposition of a single layer on a cylindrical surface in an embodiment of the present invention; wherein 1 is the movement path of the deposition origin at the end of the cladding head, 2 is the starting point of the scanning path, 3 is the ending point of the scanning path, and 4 is the cylindrical substrate.

[0038] Figure 4 1 is a schematic diagram of the laser action area in an embodiment of the present invention.

[0039] Figure 5 This is the result of fixed-point thermal cycling during single-pass multi-layer deposition in an embodiment of the present invention.

[0040] Figure 6 This is the result of the stress change at a fixed point during single-pass multi-layer deposition in an embodiment of the present invention.

[0041] Figure 7 This is a morphology diagram of the molten pool at a certain moment of single-layer multi-pass deposition in an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The present invention will be further described and illustrated below in conjunction with specific embodiments. The embodiments are merely illustrative of the present disclosure and do not limit its scope. The technical features of the various embodiments of the present invention may be combined accordingly, provided that there is no conflict between them.

[0043] The accompanying drawings are merely schematic illustrations of the present invention and are not necessarily drawn to scale. Some of the blocks shown in the accompanying drawings are functional entities that do not necessarily correspond to physically or logically separate entities. These functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0044] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all steps. For example, some steps may be decomposed, while some steps may be combined or partially combined, so the actual execution order may change according to actual circumstances.

[0045] This paper focuses on the numerical modeling and simulation of the laser metal deposition process of curved surface components, and predicts the evolution of the temperature field and stress field in the solution domain from a macroscopic perspective. The flow chart of the thermal-mechanical coupling simulation method of the robot-assisted curved surface laser metal deposition process is as follows: Figure 1 As shown, it mainly includes deposition path cross-section size calibration, geometric model establishment, grid optimization, material property setting, boundary condition setting, laser path setting, material deposition simulation and solution.

[0046] In this embodiment, a thermal-mechanical coupling simulation method for a robot-assisted curved surface laser metal deposition process mainly includes the following steps:

[0047] S1, calibrate the cross-sectional dimensions of the deposition track; during the calibration process, two partially overlapping deposition tracks are used as references to obtain the rectangular calibration dimensions, and half of the height and width of the rectangular calibration dimensions are taken as the cross-sectional dimensions of the deposition track.

[0048] In step S2, a continuous simulated deposition path is obtained based on the robot data. This continuous path is discretized into several segments. Using the calibrated deposition path cross-section, the deposition layer shape is scanned along the discrete path on the curved substrate, resulting in a geometric model containing the curved substrate and the deposition layer. Each discretized segment is considered an analysis step to be solved, and the deposition process is decomposed into discrete units using a single deposition path. Subsequent settings for laser path and material property activation are performed for this discrete analysis step set.

[0049] S3, perform initial meshing on the geometric model and optimize the mesh using corner refinement and adaptive methods.

[0050] S4, setting the material properties of the substrate and the deposition layer, boundary conditions and laser path, pre-writing the material properties of the substrate and the deposition layer in the deposition layer shape and hiding them.

[0051] S5, laser metal deposition simulation is performed based on the laser path and boundary conditions. As the laser action origin moves, the material properties of the substrate and deposited layer in the laser action area are synchronously activated, and the evolution results of the stress field and temperature field of the curved surface laser metal deposition process as the laser action area moves are obtained.

[0052] Step S1 above calibrates the cross-sectional dimensions of the deposition path. This dimension is a key parameter in numerical modeling and simulation, reflecting the combined effects of process parameters such as laser power, scanning speed, and powder feed rate during the actual process. Calibration of the deposition path cross-sectional dimensions helps verify and adjust the heat source model (laser) and the material deposition shape and performance, ensuring that simulation results match the actual process.

[0053] In this embodiment, the deposition geometry is verified by a preliminary experiment, and given parameters such as laser power, cladding speed, and overlap rate are selected for single-pass and multi-pass target material printing. Two partially overlapping deposition paths are used as a reference, and a metallographic microscope is used to calibrate the outer contour and area size of the cross-section. The height of the cross-section is used as an important parameter of the outer contour of the cross-section, and a standard rectangle is used to simplify and replace the irregular cross-section shape of the outer contour of the cross-section. Figure 2 This is a schematic diagram of the calibration of the cross-sectional dimensions of the deposition paths in an embodiment of the present invention. Taking two deposition paths with 40% overlap as a reference, its cross-section appears as an irregular semicircle under a metallographic microscope, with a width of 2.6733 mm and a height of 0.6308 mm. In order to convert it into a standard rectangle of similar area, it is preferred to use 90%-97% of the height as the height of the rectangle, and determine the width of the rectangle based on the approximate area. The height of the rectangle determined in this embodiment is 0.6 mm, and the width of the rectangle under the approximate area is 2.4 mm. Half of the height and width of the calibrated rectangle are taken as the cross-sectional dimensions of the deposition paths, i.e., the height is 0.6 mm and the width is 1.2 mm.

[0054] The above step S2 is used to establish a geometric model including a curved substrate and a deposition layer. The geometric model is the basis of the simulation. The substrate of the geometric model can be directly imported through an external model. For example, a cylindrical substrate can be used as an example. Figure 3As shown; the deposition layer of the geometric model is geometrically created by scanning the simulated deposition path along the calibrated deposition path cross-section size. In the robot-assisted laser deposition process, the simulated deposition path is obtained by reading the robot data. The deposition path corresponding to the continuous deposition process is continuous. The present invention discretizes it, decomposes the deposition process with single-channel deposition as a discrete unit, and then extracts discrete coordinate points from the single-channel deposition path curve; in order to match the posture control logic of the robot manipulator, this embodiment will generate a simulated deposition path in the form of an interpolation curve from the discrete coordinate points read from the robot data, and discretize the continuous path into several segments. The calibrated deposition path cross-section is used to scan along the discrete path on the curved substrate to form a deposition layer shape, and a geometric model including the curved substrate and the deposition layer is obtained. Taking the cylindrical single-layer multi-channel parallel deposition as an example, as shown Figure 3 As shown in the figure, reference numeral 1 represents the motion path of the deposition origin at the end of the cladding head, reference numeral 2 represents the starting point of the scanning path, reference numeral 3 represents the end point of the scanning path, and reference numeral 4 represents the substrate. The calibrated deposition path cross section is moved to the scanning path starting point 2, and the cross section is controlled to scan along the deposition origin motion path 1 at the end of the cladding head, and stops at the scanning path end point 3. The deposited layer geometry generated by cross-sectional scanning is prone to overlap with adjacent single channels or the substrate 4. This embodiment uses Boolean operations to eliminate overlapping interference between these geometric shapes.

[0055] Step S3 is used to optimize the mesh. Initial meshing is performed on the geometric model. Because large curvatures and gaps in the geometric model can make meshing more difficult and computational convergence difficult, this embodiment refines the local mesh by combining corner refinement with an adaptive method. Corner refinement involves refining sharp corners and areas with large curvature, while the adaptive method adjusts the mesh density based on the accuracy requirements of the geometric model. The higher the accuracy requirement, the greater the mesh density.

[0056] The above step S3 is used to set material properties, boundary conditions and laser paths before performing material deposition simulation.

[0057] Material properties can be calculated using specialized material performance simulation software. The accuracy of various material performance simulation software in this field has been widely verified. By inputting the material's elemental composition and heat treatment method, thermophysical parameters and mechanical performance parameters such as density, elastic modulus, Poisson's ratio, thermal conductivity, specific heat capacity, and linear expansion coefficient can be calculated at different temperatures. Material properties include those of the substrate and the deposited layer.

[0058] The boundary conditions mainly set the corresponding heat transfer boundaries and stress boundaries. In order to balance the accuracy and efficiency of the numerical model calculation, the following assumptions are introduced in the heat transfer part based on the thermomechanical coupling mechanism of laser metal deposition, and the model is appropriately simplified to take into account the accuracy and efficiency of the simulation calculation:

[0059] (1) The material is considered as a continuous medium, and the thermal properties of the material change with temperature;

[0060] (2) The physical state change of the molten pool metal only considers the solid-liquid transition and ignores the evaporation of the molten pool metal;

[0061] (3) Ignoring the microstructural evolution in the melt pool region;

[0062] (4) perform single-scale simulations;

[0063] Based on the above assumptions, the heat transfer boundaries mainly include thermal radiation boundaries, thermal convection boundaries, and phase change latent heat boundaries. Each boundary is introduced below.

[0064] The temperature evolution in the simulation area is transiently controlled by equation (1):

[0065]

[0066] in, is the material density, is the specific heat capacity, is the temperature field, is the velocity field, is the heat flow vector field, To control the heat change of the process simulation domain, is the thermal conductivity.

[0067] The thermal convection boundary is set on the surface of the geometric model that contacts the external environment. According to Newton's law of cooling, the heat loss caused by convection can be obtained by formula (2):

[0068]

[0069] in, is the convective heat transfer coefficient, is the ambient temperature.

[0070] Thermal radiation is the electromagnetic wave phenomenon emitted by an object due to its temperature being above absolute zero. The thermal radiation boundary is set at the sediment layer and its vicinity. The heat loss due to thermal radiation can be determined by the Stephen-Boltzmann formula (3):

[0071]

[0072] in, is the emissivity, which can be obtained by referring to the total emissivity table of metal materials; is the Stephen-Boltzmann constant.

[0073] According to the above analysis, the heat transfer boundary control equation for heat transfer in the deposition area, which takes into account both heat convection and heat radiation losses, is shown in Equation (4).

[0074]

[0075] During laser cladding, metal materials undergo rapid melting and solidification, which involves a rapid transition in the material's physical state. Therefore, the latent heat boundary of phase change should be considered when establishing the numerical model. The latent heat boundary of phase change is controlled in the model by modifying the specific heat capacity of the material, as shown in Equation (5).

[0076]

[0077] in, is the latent heat of phase change, is the temperature at which the material undergoes phase change.

[0078] The stress boundary is introduced below.

[0079] The stress-strain relationship of the material is described by the linear elastic model. The elastic stress tensor and the elastic strain tensor The connection is established through Hooke's law, as shown in formula (6):

[0080]

[0081] Where D is the fourth-order elastic tensor, which is composed of Young's modulus and Poisson's ratio affected by material temperature. On this basis, the nonlinear elastic deformation part must also be considered. Therefore, the total stress and total strain of the model are shown in formula (7):

[0082]

[0083] in, and is the nonlinear elastic strain and the corresponding stress, where the nonlinear elastic strain includes thermal strain and plastic strain , thermal strain uses actual temperature With reference temperature Temperature differences and temperature-dependent thermal expansion coefficients Calculate as shown in formula (8):

[0084]

[0085] For plastic strain, the Von Mises yield criterion is adopted and the isotropic hardening model is used to calculate the plastic strain, as shown in Equation (9). The yield criterion defines the stress conditions under which plastic deformation occurs. The stress outside the yield surface causes permanent deformation (plastic strain), and the stress inside the yield surface causes recoverable deformation (elastic strain).

[0086]

[0087] in, is the yield stress, is the initial yield stress, is the effective plastic strain, is the isotropic hardening modulus, is the isotropic tangential plastic modulus.

[0088] In the laser path setting, the laser speed is defined. The laser path is obtained by matching the simulated deposition path to the time axis based on the laser speed. Similarly, the laser path is discrete. In this embodiment, the laser is characterized using a Gaussian heat source model, and the laser path is controlled by the discrete coordinate points of the simulated deposition path. Based on the movement speed of the robot's manipulator during the actual deposition process, the coordinates of the coordinate points on the simulated deposition path in the X, Y, and Z directions are matched to the time variables. The laser action surface is set to the lower surface of the deposition path, and the beam direction is controlled to always be perpendicular to the action surface.

[0089] After completing the material properties, boundary conditions and laser path settings of the substrate and deposition layer, the material properties of the substrate and deposition layer are pre-written in the deposition layer shape and hidden; in this embodiment, by multiplying the various material properties of the substrate and deposition layer by a very small proportional factor, they can be regarded as non-existent in the physical sense, thereby realizing the "hiding" function.

[0090] The above step S5 is used to simulate and solve the material deposition. In this embodiment, a circular deposition area is first set around the deposition beam origin on the laser action surface to limit the laser action area, such as Figure 4 As shown, adding a range criterion activates the material properties of the deposition area, including the laser action area, while the material properties of the remaining areas to be deposited remain in an inactive state. Here, the range of the laser action area is not less than the range of the deposition path cross-sectional dimensions. Laser metal deposition simulation is performed based on the laser path and boundary conditions. As the laser action origin moves, the material properties of the substrate and deposited layer in the laser action area are synchronously activated. This embodiment uses a grid cell activation method to determine whether the grid center point is within the laser action area. If so, the material properties of the grid cell are activated, and the evolution results of the stress field and temperature field of the curved surface laser metal deposition process as the laser action area moves are obtained.

[0091] In a specific implementation of the present invention, a transient solver is used to solve the stress field and temperature field. The solution settings include tolerance setting, time step selection, time step method, etc. The solution process is common knowledge in the field and will not be described here. Taking a simple deposition on a cylindrical surface as an example, Figure 5 and Figure 6 The fixed-point thermal cycle and stress change during single-pass multi-layer deposition are shown respectively. Figure 7 The molten pool morphology under single-layer multi-pass deposition is shown.

[0092] The robot-assisted curved surface laser metal deposition process thermal-mechanical coupling simulation method proposed in the present invention can realize the geometric characterization of the laser metal deposition process for any curved surface component with a clear manufacturing process. The control of the deposition process focuses on solving the division of analysis steps, decomposing the deposition process with single-pass deposition as discrete units, and performing relevant settings for the activation of laser paths and material properties for the discrete analysis step set. The present invention designs the thermal-mechanical coupling mechanism, laser heat source design, and material activation strategy of the laser metal deposition process from an analytical perspective. While introducing appropriate simplifications to the process, it ensures the degree of restoration of the model and comprehensively considers the computational efficiency and accuracy of the numerical model. The present invention is aimed at complex curved surface components and has a high degree of modeling freedom.

[0093] Based on the same inventive concept, an embodiment of the present invention further provides a robot-assisted curved surface laser metal deposition process thermal-mechanical coupling simulation system for implementing the above method, wherein the thermal-mechanical coupling simulation system comprises:

[0094] A deposition track cross-sectional dimension calibration module is used to calibrate the deposition track cross-sectional dimension. During the calibration process, two partially overlapping deposition tracks are used as references to obtain a rectangular calibration dimension, and half of the height and width of the rectangular calibration dimension are taken as the deposition track cross-sectional dimension.

[0095] A geometric model building module is used to obtain a continuous simulated deposition path based on the robot data, discretize the continuous path into several segments, and use the calibrated deposition path cross-section to scan along the discrete path on the curved substrate to form a deposition layer shape, thereby obtaining a geometric model including the curved substrate and the deposition layer;

[0096] The mesh optimization module is used to perform initial mesh division on the geometric model and optimize the mesh using angle refinement and adaptive methods;

[0097] A pre-processing module is used to set the material properties of the substrate and the deposition layer, boundary conditions and laser path, and pre-write the material properties of the substrate and the deposition layer into the deposition layer shape and hide them;

[0098] The material deposition simulation and solution module is used to simulate laser metal deposition based on the laser path and boundary conditions. As the laser action origin moves, the material properties of the substrate and deposited layer in the laser action area are synchronously activated, and the evolution results of the stress field and temperature field of the curved surface laser metal deposition process as the laser action area moves are calculated.

[0099] As for the system embodiment, since it basically corresponds to the method embodiment, the relevant parts can be referred to the partial description of the method embodiment, and the implementation methods of the remaining modules will not be repeated here. The system embodiment described above is only illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of the present invention. Ordinary technicians in this field can understand and implement it without paying any creative work.

[0100] Embodiments of the system of the present invention can be applied to any device with data processing capabilities, such as a computer or other device. System embodiments can be implemented through software, hardware, or a combination of software and hardware. For example, a software implementation, as a logical device, is implemented by a processor of any device with data processing capabilities, reading corresponding computer program instructions from non-volatile memory into internal memory and executing them.

[0101] The above-described embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they are not to be construed as limiting the scope of the present invention. Persons skilled in the art will readily appreciate that variations and modifications may be made without departing from the spirit of the present invention, and all such variations and modifications fall within the scope of protection of the present invention.

Claims

1. A robot-assisted curved surface laser metal deposition process thermal-mechanical coupling simulation method, characterized in that: The following steps are involved: Step 1, calibrating the cross-sectional dimensions of the deposition track; during the calibration process, two partially overlapping deposition tracks are used as references to obtain a rectangular calibration dimension, and half of the height and width of the rectangular calibration dimension are taken as the cross-sectional dimensions of the deposition track; Step 2, a continuous simulated deposition path is obtained according to the robot data, the continuous path is discretized into several segments, and a deposition layer shape is formed by scanning along the discrete path on the curved substrate using the calibrated deposition path section, thereby obtaining a geometric model including the curved substrate and the deposition layer; Step 3, perform initial meshing on the geometric model and optimize the mesh using angle refinement and adaptive methods; Step 4, setting the material properties of the substrate and the deposited layer, boundary conditions and laser path, pre-writing the material properties of the substrate and the deposited layer in the deposited layer shape and hiding them; Step 5: Perform laser metal deposition simulation based on the laser path and boundary conditions. As the laser action origin moves, the material properties of the substrate and the deposited layer in the laser action area are synchronously activated, and the evolution results of the stress field and temperature field of the curved surface laser metal deposition process that moves with the laser action area are calculated.

2. The method for thermal-mechanical coupling simulation of robot-assisted curved surface laser metal deposition process according to claim 1, characterized in that: The calibration process uses two partially overlapping deposition tracks as reference to obtain the rectangular calibration size, including: Obtain actual two partially overlapping sedimentation trace samples in a pre-experimental manner; Use a microscope to calibrate the cross-sectional outer contour and area of ​​the deposition channel sample; The height of the rectangular calibration dimension is determined by taking 90%-97% of the highest point height of the cross-section outer contour as the height, and the width of the rectangular calibration dimension is determined by the approximate area to obtain the rectangular calibration dimension; The difference between the rectangular area at the rectangular calibration size and the cross-sectional area of ​​the deposition track sample is within a preset threshold range.

3. The method for thermal-mechanical coupling simulation of robot-assisted curved surface laser metal deposition process according to claim 1, characterized in that: The method of obtaining a continuous simulated deposition path according to robot data includes: Acquiring robot data, wherein the robot data includes discrete coordinate points of the action positions of the robot's mechanical arm; The discrete coordinate points are interpolated into a continuous simulated deposition path.

4. The method for thermal-mechanical coupling simulation of robot-assisted curved surface laser metal deposition process according to claim 1, characterized in that: After forming a deposition layer shape by scanning along a discrete path on a curved substrate using the calibrated deposition path cross section, the method further includes: The overlapping interference between sedimentary layer shapes is eliminated through Boolean operation.

5. The method for thermal-mechanical coupling simulation of robot-assisted curved surface laser metal deposition process according to claim 1, characterized in that: The method of optimizing the mesh by using the angle refinement and adaptive method includes: For the initially divided mesh, refine the mesh with sharp corners and large curvature; The mesh density is adaptively adjusted according to the accuracy requirements of the geometric model. The higher the accuracy requirement, the greater the mesh density.

6. The method for thermal-mechanical coupling simulation of robot-assisted curved surface laser metal deposition process according to claim 1, characterized in that: The boundary conditions include a heat transfer part and a stress part. The heat transfer part includes a heat radiation boundary, a heat convection boundary and a phase change latent heat boundary. The stress part includes an elastic stress boundary and a stress boundary generated by inelastic thermal strain and plastic strain.

7. The method for thermal-mechanical coupling simulation of robot-assisted curved surface laser metal deposition process according to claim 1, characterized in that: The laser path is obtained by matching the discrete coordinate points of the simulated deposition path with the time variable based on the laser speed.

8. The method for thermal-mechanical coupling simulation of robot-assisted curved surface laser metal deposition process according to claim 1, characterized in that: During the laser metal deposition simulation, the range of the laser action area is not less than the range of the deposition path cross-sectional size. As the laser action origin moves, it is determined whether the grid center point is within the laser action area. If so, the material properties of the grid unit are activated, otherwise they remain hidden.

9. The method for thermal-mechanical coupling simulation of robot-assisted curved surface laser metal deposition process according to claim 8, characterized in that: The laser action surface is set as the lower surface of the deposition path, and the direction of the laser beam is always perpendicular to the action surface.

10. A robot-assisted curved surface laser metal deposition process thermal-mechanical coupling simulation system, used to implement the thermal-mechanical coupling simulation method of claim 1; characterized in that: The thermal-mechanical coupling simulation system comprises: A deposition track cross-sectional dimension calibration module is used to calibrate the deposition track cross-sectional dimension; during the calibration process, two partially overlapping deposition tracks are used as references to obtain a rectangular calibration dimension, and half of the height and width of the rectangular calibration dimension are taken as the deposition track cross-sectional dimension; A geometric model building module is used to obtain a continuous simulated deposition path according to robot data, discretize the continuous path into several segments, and use the calibrated deposition path section to scan along the discrete path on the curved substrate to form a deposition layer shape, thereby obtaining a geometric model including the curved substrate and the deposition layer; The mesh optimization module is used to perform initial meshing of the geometric model and optimize the mesh using angle refinement and adaptive methods; A pre-processing module, which is used to set the material properties of the substrate and the deposited layer, boundary conditions and laser path, and pre-write the material properties of the substrate and the deposited layer in the deposited layer shape and hide them; The material deposition simulation and solution module is used to simulate laser metal deposition according to the laser path and boundary conditions. As the laser action origin moves, the material properties of the substrate and deposited layer in the laser action area are synchronously activated, and the evolution results of the stress field and temperature field of the curved surface laser metal deposition process that moves with the laser action area are calculated.

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